US4478739A - Dark colored composition based on liquid crystals - Google Patents
Dark colored composition based on liquid crystals Download PDFInfo
- Publication number
- US4478739A US4478739A US06/508,615 US50861583A US4478739A US 4478739 A US4478739 A US 4478739A US 50861583 A US50861583 A US 50861583A US 4478739 A US4478739 A US 4478739A
- Authority
- US
- United States
- Prior art keywords
- compound
- liquid crystals
- mixture
- dye
- dielectric anisotropy
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K19/00—Liquid crystal materials
- C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
- C09K19/60—Pleochroic dyes
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
- C09B1/00—Dyes with anthracene nucleus not condensed with any other ring
- C09B1/50—Amino-hydroxy-anthraquinones; Ethers and esters thereof
- C09B1/503—Amino-hydroxy-anthraquinones; Ethers and esters thereof unsubstituted amino-hydroxy anthraquinone
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
- C09B35/00—Disazo and polyazo dyes of the type A<-D->B prepared by diazotising and coupling
- C09B35/35—Trisazo dyes in which the tetrazo component is a diamino-azo-aryl compound
Definitions
- the present invention relates to a dark colored composition based on liquid crystals, especially for use in a dichroic display cell.
- a liquid crystal-base composition containing coloring agents respectively red, yellow and blue so as to confer an esthetically acceptable dark color to said composition.
- coloring agents respectively red, yellow and blue
- Black, dark blue, garnet-red and dark brown are colors which are particularly suitable for this application.
- a dye to be used for the preparation of a composition of the precited type it must present the following characteristics in addition to the required color:
- the purpose of this invention consists in providing a composition of the above mentioned type, which contains dyes fulfilling the precited requirements.
- This purpose is achieved with the composition according to the invention, which comprises a mixture of liquid crystals and dyes respectively of red, yellow and blue color, and which is characterized by the fact that the red dye is the 4,4'-bis (p-dimethyl-amino-phenylazo)-2-methyl-azobenzene of formula (I), ##STR4## the yellow dye is the 4,4'-bis (p-methoxy-phenylazo)-2-methyl-azobenzene of formula (II), ##STR5## and the blue dye is an anthraquinonic derivative represented by the general formula (III), ##STR6## in which A is H or ##STR7## and B is H or ##STR8## where R and R', identical or different, are a lower alkyl or alkoxy group, one of the A and B being H when the other is not H.
- the blue dye used is a derivative of formula (III) in which A is ##STR9## and B is H.
- the blue dye used is a derivative of formula (III) in which A is H and B is
- Composition A in the mixture of liquid crystals E43 of CHISSO, with positive dielectric anisotropy:
- Composition B (in the mixture of liquid crystals EN24 of CHISSO, with negative dielectric anisotropy):
- Composition C in the mixture of liquid crystals ALN76 of ASULAB S.A., with negative dielectric anisotropy:
- the order parameter (S) has been determined according to the known method described especially by J. Cognard and T. Hieu Phan in Mol. Cryst. Liq. Cryst. 70, p. 1282, 1981, and by measuring the optical density at the maxima of absorption of each respective constituting color.
- the measurements have been carried out (a) on the dyes which are present in the three black compositions A, B and C previously defined and taken on one part separately in the mixture of liquid crystals and on the other part in each composition, and (b) on the dyes of two black commercial mixtures respectively D 85/D86 (D85 and D86 mixed in a ratio of 1:1) (BDH) and ZLI1841/2+1843 (Merck), also taken on one part separately in the mixture of liquid crystals, respectively E63 and ZLI 1840, and on the other part in each of the two considered reference mixtures.
- the "perceived" contrast (C), corresponding to the ratio of the transmission with polarizer perpendicular to the transition moment of the dye (T ⁇ ) to the transmission with polarizer parallel to said moment (T ⁇ ), and intended to give an actual indication about the possibilities of using a colored mixture in a dichroic display cell, has been measured in the case of a black composition according to the invention (composition A) and in the case of two reference commercial mixtures, respectively D85/D86 (BDH) and ZLI 1841/2+1843 (Merck).
- composition A a black composition according to the invention
- BDH D85/D86
- ZLI 1841/2+1843 Merck
- compositions having a black color since said color is the most suitable in dichroic displays. It is however obvious that other dark colors, such as dark blue, garnet-red and dark brown, can be obtained by modifying the proportions of the three basic compounds, the qualities of the dark compositions obtained being those of the examined black compositions.
- compositions according to the invention are ideal for use in dichroic display cells, for example according to U.S. Pat. No. 4,281,903 (in the case of a mixture of liquid crystals with negative dielectric anisotropy) or according to U.S. Pat. No. 3,833,287 (in the case of a mixture of liquid crystals with positive dielectric anisotropy).
- compositions of the invention in cells of the type described by Heilmeier et al. in Mol. Cryst. Liq. Cryst. vol. 8, p. 293-303, 1969; in this case, the quantity of dichroic molecules of the mixture can be reduced, a part of the light being absorbed by a polarizer placed in front of the cell.
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Liquid Crystal (AREA)
- Liquid Crystal Substances (AREA)
Abstract
The present invention relates to a dark colored composition based on liquid crystals, especially for use in a dichroic display cell. It comprises a mixture of liquid crystals and of dyes respectively red, yellow and blue. The red dye is the 4,4'-bis(p-dimethylamino-phenylazo)-2-methyl-azobenzene; the yellow dye is the 4,4'-bis(p-methoxy-phenylazo)-2-methyl-azobenzene; and the blue dye in an anthraquinonic dye of formula (III), ##STR1## in which A is ##STR2## and B is H or ##STR3## where R and R', indentical or different, are a lower alkyl or alkoxy group, one of the A and B being H when the other is not H.
Description
The present invention relates to a dark colored composition based on liquid crystals, especially for use in a dichroic display cell.
For the realization of a dichroic display, it is particularly important to have a liquid crystal-base composition containing coloring agents respectively red, yellow and blue so as to confer an esthetically acceptable dark color to said composition. Black, dark blue, garnet-red and dark brown are colors which are particularly suitable for this application. For a dye to be used for the preparation of a composition of the precited type, it must present the following characteristics in addition to the required color:
be soluble in the liquid crystal mixture;
be photochemically stable; and
have a high order parameter.
The purpose of this invention consists in providing a composition of the above mentioned type, which contains dyes fulfilling the precited requirements. This purpose is achieved with the composition according to the invention, which comprises a mixture of liquid crystals and dyes respectively of red, yellow and blue color, and which is characterized by the fact that the red dye is the 4,4'-bis (p-dimethyl-amino-phenylazo)-2-methyl-azobenzene of formula (I), ##STR4## the yellow dye is the 4,4'-bis (p-methoxy-phenylazo)-2-methyl-azobenzene of formula (II), ##STR5## and the blue dye is an anthraquinonic derivative represented by the general formula (III), ##STR6## in which A is H or ##STR7## and B is H or ##STR8## where R and R', identical or different, are a lower alkyl or alkoxy group, one of the A and B being H when the other is not H.
According to a particular embodiment of the invention, when the mixture of liquid crystals presents a positive dielectric anisotropy, the blue dye used is a derivative of formula (III) in which A is ##STR9## and B is H.
According to another embodiment, when the mixture of liquid crystals presents a negative dielectric anisotropy, the blue dye used is a derivative of formula (III) in which A is H and B is
The invention will now be illustrated by reference to the following examples.
The three following black compositions have been prepared.
Composition A (in the mixture of liquid crystals E43 of CHISSO, with positive dielectric anisotropy):
red compound (I): 0.4%
yellow compound (II): 0.42%
blue compound (IIIa): 1.08% ##STR11## 2(p-butoxy-phenyl)1,5-dihydroxy-4,8-diamino-anthraquinone
Composition B (in the mixture of liquid crystals EN24 of CHISSO, with negative dielectric anisotropy):
red compound (I): 0.2%
yellow compound (II): 0.32%
blue compound (IIIb): 1.0% ##STR12## 3(p-butyl-phenyl-benzoate)1,5-dihydroxy-4,8-diamino-anthraquinone
Composition C (in the mixture of liquid crystals ALN76 of ASULAB S.A., with negative dielectric anisotropy):
red compound (I): 0.24%
yellow compound (II): 0.36%
blue compound (IIIb): 0.90%
Measurements of photochemical stability have been carried out on one part on the dyes used in the compositions according to the invention and separately taken in three mixtures of liquid crystals, and on the other part on these same dyes for forming the black compositions A, B and C.
For these measurements, the known method especially described by J. Cognard and T. Hieu Phan in Mol. Cryst., Liq. Cryst., vol. 70, p. 1282-83, 1981, has been used, and a "SUN TEST" apparatus of Leybold-Heraeus has been used.
The values obtained have been reported on the following Table I, in hours, corresponding to the life duration, which is defined as the time until which the measured optical density became the half of the initial value.
As it can be seen on this Table I, the photochemical stability of each composition is higher than that of the less stable component of each composition. This was unexpected since an unstable component of a composition gives in principle its unstability to the whole composition.
TABLE I ______________________________________ Stability at light (in hours) Mixture of liquid crystals ΔE > 0 ΔE < 0 Dyes E43 EN24 ALN76 ______________________________________ Compound (I) 150 <75 <100 Compound (II) 300 <150 <250 Compound (IIIa) >1000 -- -- Compound (IIIb) -- <250 <350 Composition A >500 -- -- Composition B -- >150 -- Composition C -- -- 500 ______________________________________
The order parameter (S) has been determined according to the known method described especially by J. Cognard and T. Hieu Phan in Mol. Cryst. Liq. Cryst. 70, p. 1282, 1981, and by measuring the optical density at the maxima of absorption of each respective constituting color.
The measurements have been carried out (a) on the dyes which are present in the three black compositions A, B and C previously defined and taken on one part separately in the mixture of liquid crystals and on the other part in each composition, and (b) on the dyes of two black commercial mixtures respectively D 85/D86 (D85 and D86 mixed in a ratio of 1:1) (BDH) and ZLI1841/2+1843 (Merck), also taken on one part separately in the mixture of liquid crystals, respectively E63 and ZLI 1840, and on the other part in each of the two considered reference mixtures.
The results obtained are presented in the following Tables II and III. It arises from these results that, in the case of the dyes used in the compositions according to the invention, the order parameter of each dye is higher in the composition than when alone in the mixture of liquid crystals (L.C.), whereas the reverse result is observed in the case of the examined black commercial mixtures.
TABLE II ______________________________________ Order parameter (S) of dyes used in the compositions according to the invention Order parameter (S) dye dye in dye dye in dye dye in alone com- alone com- alone compos. Dye in L.C. pos. A in L.C. pos. B in L.C. C ______________________________________ Compound 0.74 0.79 -- -- -- -- (IIIa) Compound -- -- 0.66 0.70 0.69 0.73 (IIIb) Compound 0.78 0.80 0.70 0.75 0.76 0.79 (I) Compound 0.77 0.80 0.73 0.76 0.76 0.79 (II) ______________________________________
TABLE III ______________________________________ Order parameter (S) of dyes of black commercial mixtures Order parameter (S) dye in black dye in black dye alone mixt. dye alone mixt. Dye in L.C. (BDH) in L.C. (Merck) ______________________________________ blue 0.72 0.68 0.72 0.71 red 0.76 0.74 0.74 0.71 yellow 0.75 0.72 0.76 0.72 ______________________________________
The "perceived" contrast (C), corresponding to the ratio of the transmission with polarizer perpendicular to the transition moment of the dye (T⊥) to the transmission with polarizer parallel to said moment (T∥), and intended to give an actual indication about the possibilities of using a colored mixture in a dichroic display cell, has been measured in the case of a black composition according to the invention (composition A) and in the case of two reference commercial mixtures, respectively D85/D86 (BDH) and ZLI 1841/2+1843 (Merck). This calculation method used to reach the values of the transmission from the registered spectra, is that described by A. Bloom and E. B. Priestley in IEEE Trans. Electron Devices ED-24, 823 (1977).
The results obtained are the following:
______________________________________ T⊥ (%) C = T⊥/T∥ ______________________________________ Composition A 52.5 13.98 Black mixture BDH 52.8 8.68 Black mixture Merck 53.7 7.67 ______________________________________
It can be thus seen that the perceived contrast is much higher for the composition according to the invention than for the two reference commercial black mixtures.
The above examples only concern compositions having a black color, since said color is the most suitable in dichroic displays. It is however obvious that other dark colors, such as dark blue, garnet-red and dark brown, can be obtained by modifying the proportions of the three basic compounds, the qualities of the dark compositions obtained being those of the examined black compositions.
Thus, the various physical measurements carried out, that is light stability, order parameter of the dyes and perceived contrast, show that the compositions according to the invention are ideal for use in dichroic display cells, for example according to U.S. Pat. No. 4,281,903 (in the case of a mixture of liquid crystals with negative dielectric anisotropy) or according to U.S. Pat. No. 3,833,287 (in the case of a mixture of liquid crystals with positive dielectric anisotropy). It is also possible to use the compositions of the invention in cells of the type described by Heilmeier et al. in Mol. Cryst. Liq. Cryst. vol. 8, p. 293-303, 1969; in this case, the quantity of dichroic molecules of the mixture can be reduced, a part of the light being absorbed by a polarizer placed in front of the cell.
Claims (6)
1. Dark colored composition based on liquid crystals, especially for use in dichroic display cell, comprising a mixture of liquid crystals and of dyes respectively red, yellow and blue, characterized by the fact that the red dye is the 4,4'-bis(p-dimethyl-amino-phenylazo)-2-methyl-azobenzene of formula (I), ##STR13## the yellow dye is the 4,4'-bis(p-methoxy-phenylazo)-2-methyl-azobenzene of formula (II), ##STR14## and the blue dye is an anthraquinonic derivative represented by the general formula (III), ##STR15## in which A is H or ##STR16## and B is H or ##STR17## where R and R', identical or different, are a lower alkyl or alkoxy group, one of the A and B being H when the other is not H.
2. Composition according to claim 1, in which if the mixture of liquid crystals has a positive dielectric anisotropy, then the blue dye is a compound of formula (III) in which A is ##STR18## where R is as defined in claim 1, and B is H.
3. Composition according to claim 1, in which if the mixture of liquid crystals has a negative dielectric anisotropy, then the blue dye is a compound of formula (III) in which A is H and B is ##STR19## where R' is as defined in claim 1.
4. Black composition according to claim 2, which comprises about 0.4% of compound (I), about 0.42% of compound (II) and about 1.08% of compound (IIIa), ##STR20## in a mixture of liquid crystals with positive dielectric anisotropy.
5. Black composition according to claim 3, which comprises about 0.2% of compound (I), about 0.32% of compound (II) and about 1.0% of compound (IIIb), ##STR21## in a mixture of liquid crystals with negative dielectric anisotropy.
6. Black composition according to claim 3, which comprises about 0.24% of compound (I), about 0.36% of compound (II) and about 0.90% of compound (IIIb), ##STR22## in a mixture of liquid crystals with negative dielectric anisotropy.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CH434582 | 1982-07-16 | ||
CH4345/82 | 1982-07-16 |
Publications (1)
Publication Number | Publication Date |
---|---|
US4478739A true US4478739A (en) | 1984-10-23 |
Family
ID=4274358
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US06/508,615 Expired - Fee Related US4478739A (en) | 1982-07-16 | 1983-06-28 | Dark colored composition based on liquid crystals |
Country Status (3)
Country | Link |
---|---|
US (1) | US4478739A (en) |
EP (1) | EP0099014A3 (en) |
JP (1) | JPS5924783A (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3309045A1 (en) * | 1982-03-13 | 1983-09-15 | Kabushiki Kaisha Nippon Kanko Shikiso Kenkyusho, Okayama | DICHROITIC DYES FOR LIQUID CRYSTALS AND LIQUID CRYSTAL COMPOSITIONS |
Citations (18)
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---|---|---|---|---|
US3833287A (en) * | 1973-03-08 | 1974-09-03 | Bell Telephone Labor Inc | Guest-host liquid crystal device |
US4032219A (en) * | 1974-10-21 | 1977-06-28 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britian And Northern Ireland | Liquid crystal display devices |
US4128497A (en) * | 1976-09-09 | 1978-12-05 | General Electric Company | Dichroic liquid crystal compositions |
US4145114A (en) * | 1975-06-17 | 1979-03-20 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Pleochroic dyes |
JPS55127485A (en) * | 1979-03-23 | 1980-10-02 | Toshiba Corp | Liquid crystal display device |
US4273929A (en) * | 1979-02-05 | 1981-06-16 | Hoffmann-La Roche Inc. | Heterocyclic compounds |
US4304683A (en) * | 1979-03-16 | 1981-12-08 | Mitsui Toatsu Chemicals, Inc. | Composition for liquid crystal color display element |
US4308161A (en) * | 1980-08-04 | 1981-12-29 | General Electric Company | Novel yellow azo dyes and dichroic liquid crystal compositions made therewith |
US4308163A (en) * | 1980-08-04 | 1981-12-29 | General Electric Company | Novel yellow azo dyes and dichroic liquid crystal composition made therewith |
EP0055842A2 (en) * | 1980-12-30 | 1982-07-14 | Bayer Ag | Mixtures of dyestuffs and liquid-crystal materials containing these mixtures |
US4359398A (en) * | 1980-12-22 | 1982-11-16 | General Electric Company | Liquid crystal compositions with novel tris-azo dichroic dyes |
DE3122148A1 (en) * | 1981-04-30 | 1982-11-18 | BBC Aktiengesellschaft Brown, Boveri & Cie., 5401 Baden, Aargau | Display device having a host liquid crystal and guest dyes |
JPS57192928A (en) * | 1981-05-25 | 1982-11-27 | Seiko Epson Corp | Liquid crystal display device |
US4363743A (en) * | 1980-02-26 | 1982-12-14 | Siemens Aktiengesellschaft | Liquid crystals having pleochroic dyes |
US4376715A (en) * | 1979-08-17 | 1983-03-15 | Ebauches S.A. | Composition based on liquid crystal for electro-optical device |
JPS58109579A (en) * | 1981-12-24 | 1983-06-29 | Alps Electric Co Ltd | Color liquid crystal display element |
JPS58109578A (en) * | 1981-12-24 | 1983-06-29 | Alps Electric Co Ltd | Color liquid crystal display element |
US4395350A (en) * | 1980-07-10 | 1983-07-26 | Hoffmann-La Roche Inc. | Liquid crystal mixtures |
Family Cites Families (1)
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US4179395A (en) * | 1976-09-09 | 1979-12-18 | General Electric Company | Dichroic dyes having a plurality of azo bonding groups |
-
1983
- 1983-06-25 EP EP83106214A patent/EP0099014A3/en not_active Withdrawn
- 1983-06-28 US US06/508,615 patent/US4478739A/en not_active Expired - Fee Related
- 1983-07-11 JP JP58124892A patent/JPS5924783A/en active Pending
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US3833287A (en) * | 1973-03-08 | 1974-09-03 | Bell Telephone Labor Inc | Guest-host liquid crystal device |
US4032219A (en) * | 1974-10-21 | 1977-06-28 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britian And Northern Ireland | Liquid crystal display devices |
US4145114A (en) * | 1975-06-17 | 1979-03-20 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Pleochroic dyes |
US4128497A (en) * | 1976-09-09 | 1978-12-05 | General Electric Company | Dichroic liquid crystal compositions |
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US4308163A (en) * | 1980-08-04 | 1981-12-29 | General Electric Company | Novel yellow azo dyes and dichroic liquid crystal composition made therewith |
US4308161A (en) * | 1980-08-04 | 1981-12-29 | General Electric Company | Novel yellow azo dyes and dichroic liquid crystal compositions made therewith |
US4359398A (en) * | 1980-12-22 | 1982-11-16 | General Electric Company | Liquid crystal compositions with novel tris-azo dichroic dyes |
EP0055842A2 (en) * | 1980-12-30 | 1982-07-14 | Bayer Ag | Mixtures of dyestuffs and liquid-crystal materials containing these mixtures |
DE3122148A1 (en) * | 1981-04-30 | 1982-11-18 | BBC Aktiengesellschaft Brown, Boveri & Cie., 5401 Baden, Aargau | Display device having a host liquid crystal and guest dyes |
JPS57192928A (en) * | 1981-05-25 | 1982-11-27 | Seiko Epson Corp | Liquid crystal display device |
JPS58109579A (en) * | 1981-12-24 | 1983-06-29 | Alps Electric Co Ltd | Color liquid crystal display element |
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Non-Patent Citations (6)
Title |
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Cognard, J., et al., Mol. Cryst. Liq. Cryst., vol. 68, pp. 207 229, vol. 70, pp. 1 19, (1981). * |
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Also Published As
Publication number | Publication date |
---|---|
EP0099014A3 (en) | 1984-12-12 |
EP0099014A2 (en) | 1984-01-25 |
JPS5924783A (en) | 1984-02-08 |
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AS | Assignment |
Owner name: ASULAB S.A., 6 FAUBOURG DU LAC- 2502 BIENNE, BERNE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:COGNARD, JACQUES;BASTURK, ABDURRAHMAN N.;REEL/FRAME:004147/0797 Effective date: 19830613 |
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REMI | Maintenance fee reminder mailed | ||
LAPS | Lapse for failure to pay maintenance fees | ||
STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
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FP | Lapsed due to failure to pay maintenance fee |
Effective date: 19881023 |